'It doesn't matter how tall of a wall you put up': Trump's border-wall plan is still full of holes

Donald Trump's border-wall proposal has been roundly excoriated, and despite confusion over the proposal that arose during his meeting with Mexican President Enrique Peña Nieto earlier this week, Trump has doubled down, saying that Mexico would pay for it.

"We will build a great wall along the southern border," Trump said on Wednesday night. "And Mexico will pay for the wall. ... They don't know it yet, but they're going to pay for the wall."

Leaving aside the fact that there are already fences and walls along much of the 2,000-mile frontier, Trump's proposal to cordon off the entire border with a wall anywhere from 30 to 65 feet tall is still fraught with problems, not the least of which is that such a barrier would likely not only fail to stop much of the criminality he has railed against, but it may also embolden it.

"He talks a crackdown at the border, but crossing the border is what they do best. It's where their advantage lies — that's where they make their money. That's why drugs cost so much more in the States than they do in Mexico," he said.

A Colombian antinarcotics policeman walks on packs of cocaine at the police base in Necocli, Colombia, on February 24, 2015. Reuters/John Vizcaino

A border wall may raise the prices of drugs, but it "won't do much to reduce consumption, because people who are addicted to drugs on the whole aren't very responsive to prices," Wainwright said. "So all it will succeed in doing is inflating the value of the criminal economy."

In the case of cocaine, the price goes from a few hundred dollars, for the coca leaves needed to make it in Colombia, to "more like $150,000 per kilo," when it retails on US streets, Wainwright told Business Insider, a price that would likely rise with a border wall.

"I think if the cartels could vote, they would vote for Donald Trump. His policies suit them down to the ground," Wainwright added.

'Punch a hole through it'

"Trump's wall would not have any impact on the movement of drugs through the US-Mexico border," Mike Vigil, a retired US Drug Enforcement Administration agent who spent time undercover in Mexico and Colombia, told Business Insider in March.

Secretaría de Seguridad Pública Tijuana/Facebook

"The Mexican drug traffickers would punch a hole through it, fly over it," Vigil added. "They would be able to circumvent that with medieval technology, catapults, shooting stuff across the wall."

Suggesting that drug traffickers could fly or fling drugs over a border wall is not speculation. They have done just that.

"Donald Trump is mentioning this wall like it's going to have an impact because he's playing to what people want to believe that he's going to do in terms of immigration," said Vigil. "But that wall would serve absolutely no purpose."

Boots on the ground

The necessity and benefits of a wall along the US-Mexico border have also been called into question by people who live there.

Ranchers and other residents near the border in southwest New Mexico have seen an uptick in incidents related to illegal border crossings, including break-ins and, late last year, a brief kidnapping, according to an Albuquerque Journal report from March.

But, despite these criminal incursions, residents seem wary of Donald Trump's promises "to close up that border and ... build a wall."

Central American migrants rest next to train tracks while waiting for the freight train "La Bestia," or "The Beast," to travel to northern Mexico to reach and cross the US border, in Mexico on January 10, 2012. REUTERS/Jorge Luis Plata

"The border is not secure ... It doesn't matter how tall of a wall you put up, they are going to tunnel under it, they are going to torch through it. If they want to come across, they will," Erica Valdez, who ranches more than 40,000 acres in New Mexico's boot heel, said, in what seems to be a reference to Trump's proposed border wall.

That sentiment has been echoed by international officials. Jose Manuel Salazar, the regional director for Latin America and the Caribbean for the International Labor Organization, said that the world's 232 million migrants, many of whom relocate for purely economic reasons, couldn't be contained by simple physical barriers.

"They are like a big country, one of the biggest, that goes along looking for work opportunities and keeps on growing. It cannot be turned back, it cannot be halted either with walls or those kind of measures," Salazar told EFE after presenting a report, "Labor migration in Latin America and the Caribbean," in Mexico City.

New Mexico's boot heel, comprising the southern end of Hidalgo County, borders the Mexican states of Sonora and Chihuahua. Google Maps

Rather than a static wall, residents in New Mexico's boot-heel area looked favorably on a larger US Border Patrol presence, which the agency has said it is in the process of deploying.

A more recent survey of residents on both sides of the border found widespread rejection of Trump's proposal.

A Cronkite News-Univision News-Dallas Morning News poll found that 72% of respondents on the US side and 86% of respondents on the Mexican side were opposed to building the wall.

That same survey found that 77% of Mexicans surveyed and 70% of Americans who were asked said that a wall was not important in comparison to other issues like education, jobs, and crime.

In what is perhaps a repudiation of the Republican candidate's emphasis on the wall as a means to help the US economically, 69% of those polled in Mexico said that they depend on their neighbors across the border for economic survival, with 79% of their US counterparts saying the same.